If you're reading this on a Web page, chances are you already know what URLs are. But do you understand how these Web addresses work? What most newcomers to the Web don't realize is that every single thing you see or use on the Web has a Uniform Resource Locator, or URL for short. That includes whole Web pages and things like images, scripts, movies, and sound files.

The most basic URLs (and the easiest to remember) are actually just the addresses of entire sites, like http://www.hotwired.com or
http://www.hits.org. The first part of a URL - in this case http:// - indicates the type of file you're accessing. On the Web, you'll almost always see the  letters  http,  which  stand  for  "hypertext transfer  protocol,"  because  that's  the  protocol used to transfer  Web  pages.  You'll  occasionally see  other  acronyms  or  words  in  this  space, including  ftp,  which  stands  for  "file  transfer
protocol" (you'll usually see this used to transfer software or other large files); telnet, which is used to log in to a remote computer (primarily for online "chat"); and file, which means the browser is  reading a document off your own computer rather than a remote server.



The  second  part  of  a  basic  URL  gives  your computer directions about where in this vast, global network of computer servers we call the Net to find the site you're looking for.

It does this using what's known as the Domain Name System (or DNS). Unless you're planning to set up your own Web site on your very own  machine, however, you don't really need to know much about DNS except that it's the system that gives us domain names like .com, .gov, .org, and many more that I don't have time to name. You should probably also know that DNS maps human-friendly addresses like www.hits.org to numerical IP addresses like 204.62.130.25, which computers use to recognize one another on the Internet. If you'd like to learn more about DNS, check out the column I wrote for Webmonkey on the subject.

Now, I'm sure you've noticed that once you start exploring a site, the URL in your browser's location window usually grows longer. That's because all the parts of a URL that follow suffixes like .com or .org are directions to where a specific document lives on the site's server.

To see how this works, let's dissect a URL from my mom's Web site: http://www.hits.org/community
/blocksburg/history/index.html OK, we already know that www.hits.org is just an easy way to refer to 204.32.345.61, which is the IP address of the machine that hosts this delightful little Web site. The words and slashes that follow can be illustrated most easily in an inverted tree like this:



Each word that sits between forward slashes (/) represents what's called a directory. It's probably easiest if you just think of a directory like a folder - it's a place on a server where Web site developers put pages, images, multimedia, and more directories. If we look at our example, we can  see  that  the  page  we're  looking  for, index.html, is located in the history directory,
which can be found in the blocksburg directory, which is located in the community directory.

A handy-dandy little trick you can use if you have time to explore is to start clipping text off the end of a URL. To make this work correctly, however, you must delete all the way back to a forward slash. Take my mom's URL, for example:

If you delete history/index.html from the URL in your location window, you'll go to the main page for the town of Blocksburg. This is a good way to
explore a site that doesn't have sophisticated navigation.

It's also one way to attempt to locate information that isn't where it's supposed to be. You've probably had someone give you a really long URL
once or twice that didn't quite work - maybe you received a 404 Not Found error or you simply didn't find what you expected once you got there. In cases like these, you can just start trimming off the end of the URL to poke around a little on the site. Sometimes you'll find that what you are looking for has simply moved to another area of the site. This, of course, isn't a foolproof method, but it sure doesn't hurt to try.

Remember  at  the  beginning  of  this  article  I mentioned that everything on the Web has a URL? To understand how this works, you must first understand that the HTML code for a Web page is just a text file that doesn't contain any of the images you see on a page when it's displayed in your browser - the code only contains directions to where the image exists on the server and where that image should be displayed on the page you see on your monitor. If you're curious, you can View Source on most pages to see the HTML <img src="*"> tags at work. They contain the directions (often referred to as the filepath) to the image. (If you want to learn more about how HTML works, check out the Webmonkey HTML Tutorial.)

An easier way to find the URL for an image is by clicking on it in your browser. On a Mac, simply click on the image, hold your mouse button down, and select Copy this Image Location in Netscape or Copy Image in Microsoft Internet Explorer.

On a PC in Netscape, click on the image with the right mouse button and select Copy this Image Location.  In  Internet  Explorer  on  a  PC, unfortunately, you must select Properties, copy the URL in the dialog box, paste it into your
location window, and hit Return.

The more you pay attention to URLs, view the sources of pages you surf, and experiment with altering Web addresses to explore sites' directory structures,  the  closer  you'll  come  to  truly understanding how the Net works. And that is
How URLs Work.

If you're reading this on a Web page, chances are you already know what URLs are. But do you understand how these Web addresses work? What most newcomers to the Web don't realize is that every single thing you see or use on the Web has a Uniform Resource Locator, or URL for short. That includes whole Web pages and things like images, scripts, movies, and sound files.

The most basic URLs (and the easiest to  remember) are actually just the addresses of entire sites, like http://www.hotwired.com or
http://www.hits.org. The first part of a URL - in this case http:// - indicates the type of file you're accessing. On the Web, you'll almost always
see the letters http, which stand for "hypertext transfer protocol," because that's the protocol used to transfer Web pages. You'll occasionally see other acronyms or words in this space, including ftp, which stands for "file transfer
protocol" (you'll usually see this used to transfer software or other large files); telnet, which is used to log in to a remote computer (primarily for online "chat"); and file, which means the browser is  reading a document off your own computer rather than a remote server.


The second part of a basic URL gives your computer directions about where in this vast, global network of computer servers we call the Net to find the site you're looking for.

It does this using what's known as the Domain Name System (or DNS). Unless you're planning to set up your own Web site on your very own machine, however, you don't really need to know much about DNS except that it's the system that gives us domain names like .com, .gov, .org, and many more that I don't have time to name. You should probably also know that DNS maps human- friendly addresses like www.hits.org to numerical IP addresses like 204.62.130.25, which computers use to recognize one another on the Internet. If you'd like to learn more about DNS, check out the column I wrote for Webmonkey on the subject.

Now, I'm sure you've noticed that once you start exploring a site, the URL in your browser's location window usually grows longer. That's because all the parts of a URL that follow suffixes like .com or .org are directions to where a specific document lives on the site's server.

To see how this works, let's dissect a URL from my mom's Web site: http://www.hits.org/community
/blocksburg/history/index.html OK, we already know that www.hits.org is just an easy way to refer to 204.32.345.61, which is the IP address of the machine that hosts this delightful little Web site. The words and slashes that follow can be illustrated most easily in an inverted tree like this:

Each word that sits between forward slashes (/) represents what's called a directory. It's probably easiest if you just think of a directory like a folder - it's a place on a server where Web site developers put pages, images, multimedia, and more directories. If we look at our example, we can  see  that  the  page  we're  looking  for, index.html, is located in the history directory,
which can be found in the blocksburg directory, which is located in the community directory.

A handy-dandy little trick you can use if you have time to explore is to start clipping text off the end of a URL. To make this work correctly, however, you must delete all the way back to a forward slash. Take my mom's URL, for example:

If you delete history/index.html from the URL in your location window, you'll go to the main page for the town of Blocksburg. This is a good way to
explore a site that doesn't have sophisticated navigation.

It's also one way to attempt to locate information that isn't where it's supposed to be. You've probably had someone give you a really long URL
once or twice that didn't quite work - maybe you received a 404 Not Found error or you simply didn't find what you expected once you got there. In cases like these, you can just start trimming off the end of the URL to poke around a little on the site. Sometimes you'll find that what you are looking for has simply moved to another area of the site. This, of course, isn't a foolproof method, but it sure doesn't hurt to try.

Remember at the beginning of this article I mentioned that everything on the Web has a URL? To understand how this works, you must first understand that the HTML code for a Web page is just a text file that doesn't contain any of the images you see on a page when it's displayed in your browser - the code only contains directions to where the image exists on the server and where that image should be displayed on the page you see on your monitor. If you're curious, you can View Source on most pages to see the HTML <img src="*"> tags at work. They contain the directions (often referred to as the filepath) to the image. (If you want to learn more about how HTML works, check out the Webmonkey HTML Tutorial.)

An easier way to find the URL for an image is by clicking on it in your browser. On a Mac, simply click on the image, hold your mouse button down, and select Copy this Image Location in Netscape or Copy Image in Microsoft Internet Explorer.

On a PC in Netscape, click on the image with the right mouse button and select Copy this Image Location.  In  Internet  Explorer  on  a  PC, unfortunately, you must select Properties, copy the URL  in  the  dialog  box,  paste  it  into  your
location window, and hit Return.

The more you pay attention to URLs, view the sources of pages you surf, and experiment with altering Web addresses to explore sites' directory structures, the  closer  you'll  come  to  truly understanding how the Net works. And that is
cool.

By Kristin Windbigler